Assessment of the Costs up to 2100 and Barriers to Adaptation

A quantification of climate damages or the costs of inaction faces the inherent uncertainty of future climate scenarios and socio-economic developments. For the appraisal of the long-run cost of inaction in COIN we therefore apply the Delphi technique until 2100 that offers a qualitative assessment by recognised experts rather than quantitative results. The Delphi results suggest pronounced increases in the damage costs in the second half of the twenty-first century. For half of the sectors addressed, there is unanimous consensus among experts that climate damage costs in 2070 will be higher than in 2050. A further increase in costs after 2070 is expected for the majority of sectors. Economic and social developments are considered the most important cost drivers in the long run. Despite this judgement, however, uncertainty of future social, economic and thus cost development is rated considerably high. Extreme events might be key determinants of the long-term cost of inaction.